Means of switch position indication



Dec. 5, 1950 IT. G. A. slLLERs 2,532,647

MEANS 0F SWITCH POSITION INDICATION Filed Dec. l5, 1947 i @Wg/ PatentedDec. 5, 1950 y 2,532,647 MEANS oF sWIT-onrosrrloN INDICATION Thomas G.A. Sillers, Wauwatosa, Wis., assignor to Allis-Chalmers ManufacturingCompany, Milwaukee, Wis., a corporation of Delaware Application December13, 1947, Serial No. 791,551

4 Claims.

new and improved electro-responsive switch posi-vv tion indicatingmeans.

In an electrical distribution system where relatively high voltagesobtain, it is common practice to provide switching means for isolatingindividual conductors from the system, and switching means for groundingindividual conductors that have been so isolated. In this way, aconductor may be de-energized, grounded, and given a zero potential. Solong as the conductor remains grounded it can be relatively safelyhandled, even where the conductor in question is accidentallyreconnected to the system after isolation. But the relative safecondition only persists where the conductor in question 'is positivelygrounded through the ground switching means. If the relativelyengageable contacts of the ground switching means fail to positivelyengagel upon closing, or are so corroded as to preclude a positiveelectrical connection, or become broken or inoperative, the conductorwill appear to an observer to be grounded, when actually it isungrounded. To protect personnel against the hazards of handling liveand ungrounded circuits it is necessary to provide electrical means forpositively indicating when the circuit is electrically grounded, sincemechanical indicating means merely disclose the relative-position of theswitch parts and do not give a true indication of the conductivity ofthe grounding means.

Therefore an object of the invention is the provision of new andimproved electro-responsive means for indicating the positive electricalconnection of a conductor to ground.

Another object of the invention is the provision of new and improvedelectro-responsive means for indicating the positive electricalconnection of two conductors.

Another object of the invention is the provision of new and improvedelectro-responsive means for indicating the electricalconnection of twoconductors independently of current flowing through the conductors.

Another object of the invention is the provision of new and improvedelectro-responsive means for indicating a positive electrical connectionof two conductors where the means for connecting said conductors isconcealed from view.

The novel features of this invention and how the objects are obtainedwill appear from this specication and the accompanying drawings showingseveral embodiments of the invention and forming part of thisspecication and all the novel features are intended to be pointed out inthe claims.

In the drawings:

Fig. 1 is an elevation view of apparatus comprising an embodiment of theinvention;

Fig. 2 is an elevation view of apparatus comprising an alternativeembodiment of the invention; and

Fig. 3 is a fragmentary elevation view of apparatus comprising a furtheralternative embodiment of the invention.

As shown in Fig. 1 of the drawings, the apparatus comprises anelectrical switch II, and switch position indicating means I2 therefor.The switch I I, as a single-throw knife switch in closed position,comprises a hinged blade I3 supported by a clip I4 carried by aninsulating bushing I5, the clip I4 having an outward extending terminalconnector Il. The blade I3 forms a movable contact and is swingableabout the clip I by means of an arm I8 pivotaly connected to a medianportion of the blade I, only a fragmentary portion of the arm I8 beingindicated. The arm i8 may be actuated by any suitable manual orautomatically controlled means not shown, to open or close the switch II.

The blade I3 is adapted, upon closing, to simultaneously engageconnective means comprising a stationary main contact clip I9 and astationary auxiliary contact clip 2G, the clips I9, 26 being carried bysuitable insulating means, as an insulating bushing 2l. Although a dualpurpose bushing 2l has been disclosed, individual bushings may beprovided for the respective contact clips I9, 2B without departing fromthe invention.

The main contact clip I9 and auxiliary contact clip 20 are respectivelyconnected to conducting studs 23, 261 leading through and extendingbelow the base of the bushing 2|, the stud 23 being mechanically spacedand electrically insulated from stud 2li. The contact clips I9, 26 areof unequal proportions. The main contact clip I9 normally carries therated current of the switch II and is therefore necessarily of largerproportions than the auxiliary contact clip 2i! which is adapted tocarry a relatively smaller.

signalling current.

The bushings I5, ZI supporting the switch components are fastened by anysuitable means to a base 25 of any suitable material, extending rearwardfrom a panel 26 also of any suitable material, the base 25 beingprovided with holes 27, 2Q of the propel' dimension to accommodate thedepending studs 23, 2s which, if the base 25 is of conducting material,are suitably insulated therefrom.

The switch il is adapted to connect two circuits, or as shown, twoconductors, one conductor being represented by a bus 3d, only a fragmentof which is shown, connected to the terminal connector il, and the otherconductor 3l being schematically represented by aline to ground 372, theconductor BI being connected at its other lend to the stud 23. Althoughtheconductor 3i is shown leading to ground 32V,u it may equally welllead to an ungrounded or otherwisevindependent conductor or circuit, notshown, without departing from the invention.

To indicate the open or closed position of the blade I3 of the switch IIrelative to the main ccntactclip IS, position indicating means I2, asV'nbefore nikritirilied,` is associated with the switch I'I. l The'switch position indicating means I2 comprises infs'eries circuit,anelectroresponsive ind'ioating means, shown schematically as anelectric lamp 34, and a source oipsign'alling'cur'- rent therefor, shownschematically 'as 'a battery 35. The lamp 'nayy be mounted, in anysuitable inanner, in the -panel 2t, Vwhere Yit can be visuallyoljservjerl by an 'obserr'ier standing before the panel 2E, itbeing'custoniary to interpose an insulating panel between the observerand the switch for reasons of safety.` When 'so mounted the switch IIlis concealed from the observers View, Although the lamp 34 'is shownmounted in the 'panel 26 in frontfof the switch I I, 'it may be mountedin ma separate panel, independent of andi soie distance Vfrom 'theswitch itself.

.The signalling circ'uitcomp'rising the lamp SI1 a'ridbatte'ry 35 is'connected at one of its ends throughcondiict'or Se 'and 'stud '23 vtothe main contact clip I9 and at the other of its ends through conductor3! and stud 2@ to the auxiliary contact'clip 2t. Thus the signallingcircuit may be traced from'the main contact clip I9 through stud23conducto'r B, battery 35,'1'amp 34, conductor 31, stud 2e, to theauxiliary contact clip 2p. The lsignalling circuit can only be closed byengagement 'of the switch blade i3 with the main contact clip I9 and'auxiliary contact clip 2t. Thus when the blade I3 is thrown to theclosed position as shown'in Fig. l, the signalling circuit becomesclosed and the `lamp VSli will light, indicating anelectricallyconductive v'connection between the bus 3@ and the ground 32. If thisconnection is broken, 'either through opening of theswitch II, orthrough improper contact of the vblade I3 Ywith the contact clips I9,2Q, the light will go out, indicating to the observer that the conductor3l? is ungrounded.

The stud I9 forms a direct coupling means between arst circuitcomprising the conductor 3l), and a second circuit, shown as thesignalling circuit `comprising the lamp '3s and battery 35. Thus whenthe switch blade I3 is closed on the contact clips I9, 20, the first andsecond circuits are directly coupled.

a The described switch position indicating means I2 furnishes a positiveindication of whether the switch II `is irl the electrically open orclosed position and further furnishes a positive index to the electricalconductivity of the switch contacts I3, I9 when closed. l

The switch indicating means I2, may be nondetachably connected to theswitch I I, or mayl'be detachably connected tothe switch lII in 'orderto utilize a single indicating means with a plurality of switches.

In Fig. 2 of the drawings, the apparatus shown is similar to theapparatus shown in Fig. 1 with one exception; the main contact clip 40of the embodiment of Fig. 2 extends upward a greater distance than itscompanion ,auxiliary Contact clip 20a. All other parts of the apparatusin Fig. 2 are similar to like parts of the apparatus in `Fing. 1 and areindicated by like reference charactersqfuollowed by the sufx a. As shownin Fig. 2, the switch I'Ia vis in the open position.

By extending the main contact clip el] above theylvel of -the`aiixiliary Contact clip 20a, the blade 13a of Y"the `switch IIa, uponclosing from the openposition, is obliged to first engage the :clip'lill beforeienigaging the clip Zta. |lhe sequentialmengagement of theclips se, 23a by the switch blade Ia is advantageous for the followingreason:

if the 'eoridlijr sea is riot et zero 'potentiel et velle instant thatjen-e blaue lao of the switch I'I'a 'akesconta'ctwith theclip `llt 'toground, the cl'sedswitch IIz is'oblig'edto carry fault current. Sincegthe main contact jclip 4t "and associated Stud 23a are ladptdr't the-fault cli-trent, whereas the electro-responsive indicating'means Iza isriot, it is Adesiratl-'e that'e'ny lfault'ejurrerlt owing throughItheblade '13h/be shuited from the signalling :circuit comprisingthejauxiliary contactv elip 26a, stujd `2"llja'ar'1"dlarrip 34u toground 32o. Thlsis Verleetvyelyaccomplished by extending the jr'rlalrlooritaorjellp 4s upward vas heretofore described, rgs'lti? 'for'ee 'theblade lao to rst 'engage the clipfllil before engaging `tile clip 28o,thereby'p'eventing*possibi flow of the entire fault, current 'through`'th xiliary con# reet ollp 2te 'and associated s ailing 'circuit'.

The switchcposition indicating 'niean's lf2y electrically responsive toindicate the 'po electrical connection "of the' tivofonductors 30a, Ela.rIfhe electro-respionsiv' dicatilig means is further op ativeto'i'ndicate the closed switch position ""egardless or not thecircuitfgrounde :by zero potential when the sw f' the lamp alla willlight up'n- ,u Ila even though fault 'currentislcarried 'by the switchyI Ia f ollowlin'gcliosin c A q Inl each "of, the inl/'entitleembodiments therein'- before described, las for example Athe syl/'itch II of Fig. 1,the 'connection togro 32 ismad'e throughVcor'ldl'ictil'e'studs' ,j 4, ich Aare disposed in Yspaced parallel"noliccaxral relation within the bushing 2l. iuris bro'peed, "asalternative elnbo'dimei'lt 't' f whi'ehthejoorlrleetlon to gf' c nia'det"oligh coaxially disposed 1'coiiduct'i've stl s n uppo'rted 1Qlofy asuitable bushing. According drawings, the alvparatusi'fria-gine ccomprises anelectr'ical switch `'Iib "having afni'ovf able bled-e :soIcorres'poridiilg' to tile lei-eue lf3 "of the bushing 43. The choice ofeither conducting or insulating materials for the base 44 depends uponthe type of service forwhich the switch I Ib is intended.

The main contact clips 4I and the auxiliary contact clip42 arerespectively connected to conductive studs 45, 46, leading through andextending below the base of the bushing 43. The main contact clips 4Iextend upward a greater distance than their companion auxiliary contactclip 42 to insure sequential engagement of the blade I3?) with ltheclips 4I, 42 for'reasons comparable to those recited hereinbefore forswitch I la of Fig. 2.

The stud 45 comprises a cylinder having a conductive wall dening acentral passage 4l in which the stud 45 is coaxally disposed. Interposedbetween the stud 45 and the wall of stud 45 isa cylindrical insulator 48having a radially extending upper flange 49 which insulates the clips4|, 42 one from another. The stud 45 pierces the base 44, is in contacttherewith, and extends for a short distance below the base 44. The stud45 cooperates with its associated clips 4| to clamp the bushing 43between the clips 4I and the base 44 by means of a clamping nut 5E]abutting the underside of the base 44 and engaged with the threaded endportion of the stud 45. The clamping nut 50 also serves to retain thestud 45 within the bushing 43.

A suitable terminal connector 52 is secured in electrical contact withthe stud 45 by means of a lock nut 53 cooperating with the stud 44 toclamp the connector rmly between the nuts 5D, 53.

The coaxially disposed stud 45 extends a short distance below the stud45 and insulator 48 and is retained in position relative to the stud 45by a nut 54 and insulating washer 55 cooperating with the stud 45. Aterminal connector 55 is secured in electrical contact with the stud 45in the same manner as connector 52 is secured to the stud 45, a lock nut51 retaining the connector 55 in place.

The studs 45, 45, may be severally connected to an indicating means inthe same manner as are the studs 23, 24, in Fig. 1. And if the switchIIb is to be used as a grounding means the stud 45 may be connected toground as is the stud 23 in Fig. 1.

When the stud 45 is connected to ground, a`

conducting material such as steel may be used for the base 44, and thebase 44 connected to ground by suitable means, not shown.

The operation of the switch lib is similar to the operation of switch Ila in that fault current when present is induced to flow through themain stud 45, the current being shunted from the auX- iliary stud 46forming part of a signalling circuit not shown; the function of stud 46being comparable to the function of stud 24a in Fig. 2.

By providing two contact clips 4l engageable by the blade I3b, moreswitch contact points are made available and the contact resistance ofthe switch IIb is substantially reduced. Furthermore by having multiplecommon contact clips, the chance of accidentally opening the switchthrough burning off of one clip is materially reduced.

As illustrated in the various gures, the switch I I is adapted foroperation in an insulating uid medium, such as air. However, the switchIi may be operated submerged in an insulating iiuid such as oil. When sooperated the embodiment of lig 3 is preferred.

From the foregoing it will be apparent to those skilled in the art thatthe illustrated embodi- 6j ments of the invention provide a new andimproved electro-responsive switch indicating means and accordinglyaccomplishes the objects of the invention.

On the otherl hand, it will be obvious to those skilled in the art thatthe illustrated embodiments of the' invention may be variously changedor modied, or features thereof, singly or collectively, embodied inother combinations than those illustrated, without departing from thespirit of the invention, or sacriiicing all of the advantages thereof,and that accordingly the disclosure herein is illustrative only and theinvention is not limited thereto.

It is claimed and desired to Patent:

1. In an electrical switch, a pair of insulating bushings, a movablecurrent-carrying contact supported by one of said bushings, a pluralityof conductive assemblies supported by the other of said bushings, eachof said assemblies comprising a conductive stud and at least oneengageable contact clip connected to said stud, one of said studs beingdisposed in coaxial relation with respect to another of said studs forproviding several current paths through said other of said bushings, andsaid clips being arranged in stepped relation with respect to saidmovable contact whereby said movable contact engages at least one ofsaid clips connected to said one of said studs prior to engaging anotherof said clips connected to said another of said studs upon closing saidswitch against said clips.

2. A ground safety device comprising an electro-responsive indicatingmeans and a source of current exclusively therefor, said source ofcurrent having terminals of opposite polarities, one of said terminalsbeing connected to said indicating means, a ground lead, a conductor, aswitch comprising a movable contact and first and second contactsconductively engageable by said movable contact for connecting saidconductor to said ground lead through said rst contact, said secondcontact interconnecting said indicating means with the other terminal ofsaid source of current through said movable contact for causingenergization of said indicating means only if said movable contactconnects secure by Letters said conductor to said ground lead throughsaid movable contact and said rst contact.

3. A control device for controlling the connection between a firstcircuit and a second circuit and for energizing a signalling circuitcomprising indicating means and a source of current exclusively thereforfor manifesting an electrically conductive connection between said rstcircuit and said second circuit comprising in combination, a contactelement connected with said second circuit and with said signallingcircuit, another contact element connected with said rst circuit, athird contact element connected with said signalling circuit, andcontact means simultaneously engageable with said rst, second and thirdcontact elements to establish an' electrical connection between said rstand second contact elements for connecting said rst and second circuitsand between said second and third contact elements for feeding currentfrom said source only to said indicating means through said contactmeans.

4. In an electric switch, a pair of insulating bushings, a movablecontact supported by one of said bushings, a plurality of conductiveassemblies supported by the other of said bushings. each of saidassemblies comprising a conductive stud and at least vone engageablecontact Tclip vconnected to said stud; one of said studs being disposedin coaxial lrelation with respectto another of said studs for providing`several current paths through vsaid other of said bushings. and 'saidclips being of substantially equal length whereby said movable Contactengages said clips substantially'simultaneously upon closing of saidswitch `against said clips.

THOMAS G. A.SILLERS.

REFERENCES CITED The following references are of record .in the le ofthis patent: f

yNumber Number 8 UNITED ASIAIES PATENTS Name Date Wright Oct. 27, 1903Ayer Aug. 30, 19,01 Robertson Nov. 15, '1904 Hewlett Apr. l9, 1907Lincoln Jan. 28, 1908 Bakken Nov. 15, 1927 FQREIGN PATENTS Country DateGreat Britain Nov. 6, 1924

